Paul’s first visit to Corinth was in AD50 and is described in Acts 18:1-18.
Some time later, probably around AD55, it seems he made another visit to Corinth, foreshadowed in 1 Corinthians 4:19; 16:5-8. It is often described as his “painful visit” because of Paul’s later comment in 2 Corinthians 2:1.
His third visit is mentioned in 2 Corinthians 12:14; 13:1 and described (briefly) in Acts 20:2-3. This was probably in AD57.
We do not know of any subsequent visits, although it is possible (even likely) that Paul returned to Corinth as he travelled extensively after being released from prison in Rome in about AD63.